The present study will determine the mechanisms of control of fatty acid metabolism in cardiac muscle. Experiments are proposed which will determine control of fatty acyl CoA synthetases, carnitine-acyl CoA transferases, and transport of acyl carnitine across the mitochondrial membrane. The effects of increased ventricular pressure development and availability of exogenous fatty acid on these steps of fatty acid oxidation will be investigated in the isolated perfused rat heart. BIBLIOGRAPHIC REFERENCES: Neely, J.R., K.M. Whitmer and S. Mochizuki. Effects of mechanical activity and hormones on myocardial glucose and fatty acid utilization. Harry S. Moss Symposium on Regulation of Cardiac Metabolism, Dallas, Texas, May 19-20, 1975. Circ. Res. 38: Suppl. 1, I-22 to I-30, 1976. Neely, J.R., M.J. Rovetto and J.T. Whitmer. Rate-limiting steps of carbohydrate and fatty acid metabolism in ischemic hearts. Experimental and Clinical Aspects on Preservation of the Ischemic Myocardium. Editors H. Ake and L. Werko. Acta Medica Scandinavia, Supp. 587: 9-15, 1975.